a. Field of the Invention
The invention relates to processes, devices and systems for the highly effective and efficient treatment of waste fluids, and in particular for the highly effective and efficient oxidation of contaminates in waste fluid. Oxidation reactions are carried out in multi-stage, co-current, plug flow reactors.
b. Background Art
Organic and non-organic industrial, agricultural and municipal waste materials are a prevalent and growing problem throughout the industrialized world. For example, industrial chemicals, pesticides, personal-care products and pharmaceuticals have been found in wastewater streams throughout the United States. Oil, mining and chemical refining facilities are key targets. These organic waste materials present environmental hazards, especially when the waste levels exceed EPA standards.
Treating waste materials in a wastewater or waste fluid is an area of active study. A number of techniques have been developed for the destruction of organic materials in a waste fluid, several of which are discussed in greater detail below. Although several of these techniques have been useful in the partial destruction of lower organic concentrations, few if any have proven effective or efficient at treating sources with higher concentrations of organic waste, for example waste fluids having more than 100 mg/l organic contaminates.
U.S. Pat. No. 6,093,328 discloses the use of hydrogen peroxide and solid particles formed between elemental iron and sulfur to remove arsenic and total organic carbon from water. The reaction is carried out at or below about 100° C.
U.S. Pat. No. 5,928,522 discloses a process for treating oil refining waste where large particles and waxy materials are removed and the remaining liquid is drawn off and centrifuged. The residual cake is treated with hydrogen peroxide and water to form a slurry which is heated to 100° F.
U.S. Pat. No. 6,251,290 discloses the use of hydrogen peroxide in a limited Fenton reaction to treat hydrocarbon ore at 60° C. to 100° C. This results in the partial oxidation of the hydrocarbons.
Hydrogen peroxide has further been used in a number of applications to treat fluids containing various waste materials. For example, in U.S. Pat. No. 6,051,145, and related U.S. Pat. No. 5,888,389, a multi-stage treatment of sewage sludge is disclosed using a first stage sub-critical pressure of between about 3,600 psi to 4,500 psi. The second stage is run at a higher temperature to produce super critical oxidation conditions.
U.S. Pat. No. 5,240,619 discloses a process characteristic of a super-critical oxidation. This process utilizes oxygen containing gas and pressures well in excess of the super critical pressure, e.g., 350 atm. The super critical pressure is applied in a first stage reaction at a temperature between 250° C. and 374° C. The second stage reaction is carried out at the same pressure and temperature between 374° C. and 600° C. This results in super critical oxidation conditions in the second stage reaction.
U.S. Pat. No. 6,080,309 discloses a process for the separation of impurities from liquids. In this process, a centrifuge is used to achieve temperatures and pressures which are no lower than 705.4° C. and 3,208 pounds per square inch. Such conditions exceed the super critical pressure and temperature of water. After reaching super critical conditions, oxygen in any form is introduced into the suspension. An oxidizing reagent such as hydrogen peroxide may be used.
The chemistry of advanced oxidation reactions can be quite complex.
U.S. Pat. No. 3,782,163 relates to a process for the ozone treatment of liquid material. The process includes introducing a major part of the liquid into a first ozonation zone and introducing the remainder into a second ozonation zone. The oxidation apparatus comprises two packed columns. The packing material can be raschig rings. The waste flow within the reactor is countercurrent with the flow of ozone within the reactor. The pH of the waste streams is at least about 12. The two reactors are necessary to complete the oxidation reaction.
U.S. Pat. No. 4,028,246 is directed to a liquid purification system. The system includes an airtight casing having a plurality of panels dividing the interior on the casing into a plurality of sections to form an ozone liquid contact chamber. The liquid runs down the panels and casing walls in a falling thin film. Ozone is introduced in the casing under pressure between 2 and 10 psi. The ozone flow contacts the liquid running over the panels. The flow of ozone and liquid is moving from the top of the casing to the bottom. No packing material is disclosed.
U.S. Pat. No. 4,229,296 describes a wet oxidation system employing a gas separation reactor. A waste water flow is directed to a bottom region of a first vertically elongated reaction zone at a first flow rate. An oxygen containing gas is charged to a bottom region of the reaction zone at a second flow rate. A lower liquid phase is separated from an upper gas phase. An aqueous liquid effluent is removed from the middle region of a plug flow type reaction zone wherein mixing in a traverse reaction zone occurs but which allows for no diffusion in the flow direction. The flow rates of the waste water in the oxygen containing gas are not the same. Composition of the reactant mixture varies along the flow path. The reactor is directed to operate at temperatures ranging from about 350° to 600° F. at pressures ranging from about 800 to 2200 psig. Waste water contains from about 0.8 to 3 weight percent of organic matter on a 100 weight percent basis. The reactor does not have a diffuser plate or a series of surfaces packed inside the reactor.
U.S. Pat. No. 5,364,537 discloses injection of hydrogen peroxide and ozone in flow direction co-current with circulation of water to be treated. The patent does not disclose a packed reactor or plug flow.
U.S. Pat. No. 5,851,407 claims a water decontamination process. The process comprises injection pressurized flow of hydrogen peroxide and ozone in a flow of contaminated water. The ozone and hydrogen peroxide are injected at velocities and directions matching those of contaminated water flow. The system for decontaminating water includes a high intensity mixer. The patent does not disclose a packed reactor.
U.S. Pat. No. 6,024,882 is a continuation-in-part application of U.S. Pat. No. 5,851,407. The '882 patent discloses a process and apparatus for exposing water to oxidizing conditions under pressure. A combination of ozone and single dose of hydrogen peroxide is added to the water but, under pressure, at an acidic pH and with high intensity mixing. The disclosure is focused on the control of bromate contamination in the water.
U.S. Pat. No. 6,054,057 is directed to a method for processing a feed material. The feed material can include an oxidant such as hydrogen peroxide, oxygen and air. The method includes initiating reaction by jet mixing the feed material in a back-mixing section of a reaction chamber, carrying out an additional reaction in the reaction stream in a plug flow section of the reaction chamber. Injection of feed material is through the top of the reaction chamber. The patent does not claim co-current flow of waste material.
U.S. Pat. No. 6,214,240 discloses that reaction in an ozone treatment using ozone mixed with hydrogen peroxide is very complex, because many reactions simultaneously take place and the reactions interfere with each other. The disclosure is directed to a computer simulation model and apparatus. It claims the use of a mixture of hydrogen peroxide and ozone for the ozone treatment of an effluent. Ozone concentrations are below 300 mg/l. The process is based on a volumetric mass transfer coefficient. The patent does not disclose the structure of the reactor or co-current flow of ozone and effluent. It does not teach a mass transfer of kinetics and oxidation rate in terms of time versus volume and time.
Ozone treatment of effluent using ozone mixed with hydrogen peroxide is a very complex reaction. A variety of apparatus and a variety of methods have been utilized as a result of the complexity of the reaction process. Applicants have advanced the treatment of such complex reaction systems by utilizing co-current flow of fluids in the substantial absence of back mixing during the effective life of ozone. Applicants now describe their invention in greater detail.